Update docs for CheckReturnValue

[izeye]

The "How to tell Error Prone which methods to check" section doesn't seem to reflect the changes made in #435.

It also would be better to expand the "Ignored contexts" section to fully reflect the following:

error-prone/check_api/src/main/java/com/google/errorprone/matchers/Matchers.java

Lines 1330 to 1353 in b1631fe

	/**
	* {@link FunctionalInterface}s that are generally used as a lambda expression for 'a block of
	* code that's going to fail', e.g.:
	*
	* <p>{@code assertThrows(FooException.class, () -> myCodeThatThrowsAnException());
	* errorCollector.checkThrows(FooException.class, () -> myCodeThatThrowsAnException()); }
	*/
	// TODO(glorioso): Consider a meta-annotation like @LikelyToThrow instead/in addition?
	private static final Supplier<ImmutableSet<Type>> CLASSES_CONSIDERED_THROWING =
	VisitorState.memoize(
	state ->
	Stream.of(
	"org.junit.function.ThrowingRunnable",
	"org.junit.jupiter.api.function.Executable",
	"org.assertj.core.api.ThrowableAssert$ThrowingCallable",
	"com.google.common.truth.ExpectFailure.AssertionCallback",
	"com.google.common.truth.ExpectFailure.DelegatedAssertionCallback",
	"com.google.common.truth.ExpectFailure.StandardSubjectBuilderCallback",
	"com.google.common.truth.ExpectFailure.SimpleSubjectBuilderCallback",
	"com.google.devtools.build.lib.testutil.MoreAsserts$ThrowingRunnable",
	"com.google.gerrit.testing.GerritJUnit$ThrowingRunnable")
	.map(state::getTypeFromString)
	.filter(Objects::nonNull)
	.collect(toImmutableSet()));

See https://errorprone.info/bugpattern/CheckReturnValue

[nvssai11]

Thanks for the detailed report and repro. I’d like to work on this issue and help fix the uninitialized vtable values. Could you please assign it to me?